1. Field of the Invention
The present invention is related to the field of handling voice telephone call connections, and more specifically to devices, softwares and methods for handing off voice telephone calls made between circuit switched telephone connections and data network packet switched connections.
2. Description of the Related Art
Traditionally telephone calls are handled through connections that use circuit switching. These connections are also known as circuit switched voice connections.
Current networks for cellular communication devices (such as cellular telephones) are characterized as 2G/2.5G, which means “second generation”, and “second and a half generation”. These, along with the first versions of 3G (“third generation”) cellular networks, use circuit switched connections for voice calls.
Packet switched networks, such as the internet, were initially intended to be for transmitting data, which is why they are also sometimes called data networks. Packet switched networks can also handle telephone calls. Connections for voice telephone calls through a network are also called packet switched connections.
In a packet switched connection across a data network, the voice data of a conversation is transmitted in data packets, using a suitable voice over data network (VoX) protocol. A VoX protocol, also known as merely VoX, is an application that operates on top of the data network. Such VoX protocols include but are not limited to the Voice over Internet Protocol (VoIP), the Voice over Frame Relay (VOFR) protocol, Voice over Asynchronous Transfer Mode (VoATM) protocol, etc.
Wireless LANs (Local Area Networks) are packet switched, and can provide voice service using VoX. These wireless LANs (“WLANs”) include those operating under the IEEE 802.11b/a standard. “IEEE” stands for the Institute of Electrical and Electronics Engineers, an organization maintaining a website at <http://www.ieee.org/> at the time that this document is initially filed with the U.S.A. Patent Office.
For data transmission services, multimodal WLANs and cellular handsets might use either WLANs or cellular connections. In fact, it is even possible to perform a data handoff between legs of communication that are of disparate such modalities.
It is desired to have a way to hand off telephone call connections between the CSV modality and the VoX modality.